1. Field of the Invention
The present invention relates to the technical field of additive manufacturing, in particular the optimization of a production process for a component to be produced by additive manufacturing, by means of a simulation of the production process.
2. Description of the Related Art
Additive manufacturing (AM) is a manufacturing method that is becoming increasingly important. Machines for producing components which meet industrial standards have in the meantime become commercially available. It is anticipated that in the coming years, these machines will replace conventional production processes in many sectors.
In contrast to subtractive methods, production processes based on AM build up the object by the successive addition of material. In the process, a noncohesive material is applied in layers in a production space (also referred to as a fabrication space, construction space, or space), and in each case the components which make up the part to be produced are cohesively joined together. Thus, in stereographic methods, synthetic resin baths are used which may be hardened in layers using a UV light beam, and in laser sinter methods, pulverized powder is welded together in layers.
A typical design process 100 for a component to be produced by additive manufacturing is illustrated in FIG. 1. Based on the predefined geometric design 102, design changes in the internal structure may be made in a method step 104. A cyclical iteration by means of analysis, simulation, and optimization methods 108, based on redesign cycles 106, often takes place here. After this product design process 101, the actual production process 110 begins with design of the production method 112, i.e., how the 3D printer is to be configured for the production, and which design (together with any supporting structures) is ultimately produced. A design for supporting structures is created in method step 114. A cyclical iteration by means of a data integrity check 118, based on redesign cycles 115, often takes place here.
In an AM machine process 120, slice generation is performed in method step 116, and AM process parameters are determined in method step 119. Machine process control data are generated from the generated slices 116 and the AM process parameters 119 in method step 122, on the basis of which the AM product 130 may be produced in the 3D printer.
In the production of high-quality components, which are required in many industrial products, three key challenges arise in the planning of the production process: First, the selection of the machine parameters of the 3D printer, such as the intensity of the laser, determines the quality of the components, for example the durability. However, the precise selection of the machine parameters is not trivial, and in many cases requires a great deal of experience as well as multiple iteration cycles in order to identify the optimal machine parameters. Second, the powder and the component to be produced have different densities, so that supporting structures must be additionally inserted in order to guarantee the required accuracies of the component. For geometrically complex structures, partial areas of a nevertheless cohesive object which are not supported in the gravitational direction by the object itself, but, rather, which subject the object to tension in the gravitational direction on a suspended material overhang, are frequently observed (comparable, for example, to a mast having a downwardly pointing boom). During slice generation, this results in noncohesive cross sections in these types of objects, which in the powder bath would initially not be supported by underlying portions of the actual geometry, and during the production would thus rest only on noncohesive powder. In practice, such situations may also be avoided by adding additional supporting structures. These additional supporting structures result in consumption of extra material, as well as a further machining step in which they must be removed. The selection of the supporting structures and the precise placement of the component to be produced (which ultimately implicitly determines the number of necessary supporting structures) also requires a great level of effort, a wealth of experience, and often, multiple iteration cycles. Third, an unfavorable selection of supporting structures may have an adverse effect on the quality of the component in such a way that production-induced residual stresses in the supporting structures flow into the actual component, resulting in permanent parasitic deformations.
Heretofore, the exact placement/orientation of the component and supporting structures has been carried out manually. The outcome cannot be assessed until after production.
The challenges have thus far been addressed by a manual approach. Automation of the derivation of optimal process parameters has been proposed in “Optimal dimensional and mechanical properties of laser sintered hardware by thermal analysis and parameter optimization” (U.S. 2009/0326706 A1).
On account of the manual approach to these three challenges, a considerable amount of time has been lost from development, up through production, of the actual component. However, the size of the object to be produced by additive manufacturing is increased by unnecessarily large supporting structures, which likewise slows down the actual production process.
Conventional software for automatically generating supporting structures identifies, based on a given criteria catalog, for example angles of surfaces, a surface that requires support. However, the supporting material itself is not optimized with regard to the material used; essentially, simple columns are formed.
Since supporting structures require post-machining (removal using subtractive methods), designs which require (many) supporting structures are not advantageous, in particular when the areas in which supporting structures are needed are not easily accessible.
The object of the invention, therefore, is to overcome these disadvantages.
This object is achieved by the approaches described in the independent claims. Advantageous embodiments of the invention are set forth in the further claims.